In the formation of articles having reflective surfaces, such as a reflector for automotive vehicle headlights, it has been the prior practice to provide a reflective coating of a metal, e.g. silver or aluminum, on the surface of a preformed synthetic resin or plastic substrate, and to coat the reflective surface thus formed with a protective layer, e.g. of a transparent lacquer which may also be a synthetic resin material.
The reason for the protective coating, of course, is that the reflective layer is mechanically sensitive, i.e. abrades readily upon contact, and is susceptible to oxidation in the atmosphere, an oxidative reaction giving rise to a change in the reflectivity properties.
The principal drawback of the earlier system for fabricating such reflectors, therefore, is that it requires the application of a protective coating, frequently from a solvent based system in an environmentally hazardous and expensive procedure. The cost of the reflective body, therefore, is relatively high.
Mention may also be made of the fact that it is frequently desirable to control the degree of reflectivity of a particular surface applied to a synthetic resin substrate. This is not easily done with conventional processes.
Furthermore, reference may be had to the state of the art involving arc techniques for forming a deposit of a material on a surface. In arc sputtering and other techniques of this type, there is a substantial problem with droplet spattering, an effect which is detrimental to the uniformity of the coating which is applied. It has thus been long desired, utilizing arc techniques, to avoid droplet spattering.